(A) Field of the Invention PA1 (B) Description of the Prior Art
The present invention deals with air and water hoisting equipment and the like. More particularly, the present invention relates to air and water cranes, and deals with hoisting machines using basically building up buoyancy forces to lift up and lower down loads between different levels, and to support them.
For lifting, supporting, loading and unloading heavy loads, the industry uses heavy massive machinery using heavy supporting structures in conjunction with different diameter pulleys and cables, and pressurized fluid, forcing up pistons to lift up with their attachments to the required level.
Such hoisting systems are cumbersome, costly and heavy to transport and to move around and the fluid pressure requires special heavy steel cylinders and pistons to contain it and very elaborate joints to avoid escaping of the pressurized fluid.
Besides, to transport a large capacity crane from one country to another or from the city to the oil fields or the like, it would be very costly and sometimes impossible to get the crane where it is needed.
British Patent Specification No. 1,421,096 describes a pneumatic telescopic hoist which uses pressurized air or gas to lift up its loads. U.S. Pat. No. 3,734,464 discloses a control system for multi-stage lift which uses pressurized air to lift up its loads and keeps the lower stages overpressurized for better stability of the system.